FAP Disease

1 What is Familial Adenomatous Polyposis?

Familial adenomatous polyposis (FAC) is a hereditary disease that causes the development of polyps mostly in the colon and rectum, although they can also develop in the small intestines especially in the duodenum.

These polyps are benign but with time they may eventually become malignant.

The best treatment option is having surgery in which the polyps are removed before they can become malignant.

2 Symptoms

The first signs and symptoms familial adenomatous polyposis develop from early adolescence and get worse with time since more polyps grow.

The polyps may bleed causing blood to be present in stools. Sometimes bleeding might be silent (no blood will be seen in stools ). In such cases anemia in the patient can be the only sign of bleeding.

If the polyps become malignant, the cancer may spread to the liver.

Metastasis is usually accompanied by weight loss.

The location of the polyps depends on the nature of the defect in the APC gene.

3 Causes

The cause of familial adenomatous polyposis is a mutation in APC gene , which is a tumor suppressor gene.

This gene is located on band 5q21.

This mutation leads to the inactivation of APC protein.

4 Making a Diagnosis

The first step in diagnosing familial adenomatous polyposis (FAP) is to take the history of the patient since this disease is hereditary ( passed from parents to children).

Imaging tests can then be performed to look for polyps in the intestines.

Imaging tests used include:

  • X-ray imaging, the patient takes barium before the x-ray is performed so that the intestines can be better visualised-colonoscopy or sigmoidoscopy, in which an endoscope (tube with a camera at one end ) is inserted into the colon through the anus. This allows doctors to check if polyps are present in the colon. If polyps are present, a biopsy can be taken for further histologic studies a CT scan or an MRI of the pelvis and abdomen are usually used to evaluate desmoid tumors
  • Genetic tests can be performed to look for mutations in the APC gene. A complete blood count (CBC) can also be performed

5 Treatment

Treatment for familial adenomatous polyposis is usually surgery to remove the polyps. This is usually done when a patient has an increased number of polyps or is at a high risk of developing cancer.

Surgery is mostly performed in patients with the APC mutation that will later develop cancer by the time they are 40.

Prophylactic surgery can also performed in those younger than 25.
Several surgical procedure exist in which either the colon or rectum or both are removed.

However, surgery does not cure AFP since polyps can still grow in the remaining part of the intestines.

One of the following surgical procedures can be performed to remove polyps:

  • Ileal pouch-anal anastomosis (J pouch ) surgery , in which the rectum and colon are removed but the anus is preserved and attached to the small intestines (ileum). One disadvantage of this procedure is that it can affect fertiliy
  • Total colectomy, only the colon is removed while the rectum and anus are preserved.
  • Continent ileostomy, the small intestine is connected to the outside of the body through an opening in the abdominal wall, bowel movements are collected into a bag since the rectum or anus is damaged

6 Risks and Complications

Familial adenomatous polyposis is may be lead to the following complications:

  • Colorectal cancer
  • Cancer of the small intestines particularly of the duodenum
  • Cancer of other organs if metastasis occurs, for example, gastric cancer, thyroid cancer, pancreatic cancer and others.
  • Desmoids, noncancerous masses that can arise anywhere in the body although they mostly develop in the abdomen. They can cause serious problems if they grow into nerves or blood vessels or exert pressure on other organs in the body.
  • Noncancerous bone tumors
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